The present invention relates to a control device method for plate material hot rolling equipments for width control with which a plate material (rolled material) fed from a continuous casting equipment is rolled into a desired plate width.
In these days, with technical advance of continuous casting equipments, it has been developed to practice continuous rolling by successively supplying a plate material fed from the continuous casting equipment to a finish mill. Such continuous rolling makes it possible to achieve reduction of labor and enhance the manufacturing efficiency of plate materials.
Meanwhile, there has been endeavored to increase the capacity of an ingot melting container, called a tundish, in continuous casting equipments. An increase in the capacity of the ingot melting container requires to change a width of plate material during continuous rolling. Some types of continuous casting equipments can accommodate such a change in plate width to some extent. However, most of well-known continuous casting equipments have a difficulty in rapidly, high-accurately and easily adapting to the various demands of change in plate width.
To overcome the foregoing difficulty, it has been proposed to dispose a vertical mill on the delivery side of a continuous casting equipment and then roll a plate material to any desired width. The plate width can easily be changed by varying a roll spacing of the vertical mill. This type arrangement is disclosed in Japanese Patent Laid-Open No. 60-186106 (1986), for example. Note that in Japanese Patent Laid-Open No. 61-186106 (1986), a plurality of vertical mills are disposed to prevent the plate material from buckling. Further, in Japanese Patent Laid-Open No. 61-186106 (1986), a horizontal mill is disposed on the delivery side of the vertical mill to make up each stand group comprising a vertical mill and a horizontal mill in pair. Though not explicitly stated, it is believed that the horizontal mill has a function to roll the plate material into a desired thickness.
When rolling of a plate material into a desired width is carried out by a vertical mill on the delivery side of a continuous casting equipment, the plate material requires to be preloaded with a tensile force from the viewpoint of preventing it from buckling. On the other hand, since no rolling process is included between the continuous casting equipment and the vertical mill, a fragile structure, called dendrite, composed of principally impurities is formed on the surface portion of the rolled material. Therefore, in case of rolling the plate material to a desired width by the vertical mill, it is desired to impart a minute tensile force at a necessary minimum level to the rolled material.